Ammonium nitrate explosives



AMMONIUM NITRATE EXPLOSIVES Leonard A. Stengel, Terre Haute, Ind.,assignor to Cornmercial Solvents Corporation, New York, N.Y., acorporation of Maryland No Drawing. Filed June 4, 1959, tier. No.819,530

7 Claims. (Cl. 52-44) My invention relates to new ammonium nitratecompositions suitable for use as explosives and for making explosivescontaining ammonium nitrate and an amino compound represented by thestructural formula where R is selected from the group consisting oflower alkyl, lower hydroxyalkyl and C H NH and R is selected from thegroup consisting of hydrogen, lower alkyl and -C H NH and to processesfor using same.

Ammonium nitrate has long been known to be flammable and explosive andthese properties have been made use of extensively, ammonium nitratebeing now widely used as an explosive although it possesses certaininherent disadvantages, such as low density, and relative insensitivitywhen used as an explosive.

While these low density ammonium nitrate explosives are satisfactory forcertain situations involving relatively easy biasting, they cannotdevelop the detonation velocities and bore hole pressures needed inblasting hard rock difiicult to fracture. The ammonium nitrate-aminocompositions of my invention, however are of relatively high densityranging from 1.0 to 1.5 and are sufficiently sensitive for practicalapplication in blasting without any manufacturing steps or ingredientsnot readily, simply and safely performed and used at the site. Highdensity ammonium nitrate mixtures of this range used in the past haveeither involved a sensitizer more sensitive and dangerous to handle thanthe ammonium nitrate and hence such mixtures were difficult to store,ship, handle and mix with other ingredients or they involvedmanufacturing steps diflicult to carry out in the field.

It is extremely dangerous to prepare ammonium nitrate explosivescontaining trinitrotoluene or other similar explosives outside of apermanent industrial explosives factory meeting all known safetyrequirements and operated by personnel experienced in the manufacture ofexplosives. Furthermore, the ammonium nitrate and carbonaceous materialordinarily used therewith must be thoroughly mixed and combined inequipment which is only found in an industrial plant for the manufactureof explosives. As large amounts of ammonium nitrate and sensitizers arealways present in factory operations, there is the ever-present dangerof disastrous explosions which may demolish the area surrounding theindustrial plant for the production of explosives.

I have now discovered that combinations of ammonium 2,976,132 PatentedMar. 21, 196i nitrate with varying amounts of amino compoundsrepresented by the structural formula Hat where R is selected from thegroup consisting of lower alkyl, lower hydroxyalkyl, and C H NH and R isselected from the group consisting of hydrogen, lower alkyl and C H NHranging from 2 to 50% by weight, based on the weight of the mixture, canbe advantageously employed either as explosives or in the preparation ofexplosives. Compositions containing the amino compounds hereinabovespecified in amounts ranging from 2-14%, and preferably in amountsranging from 6-8% by weight, based on the weight of the mixture,constitute effective explosives and are generally more effective as suchthan other previously known ammonium nitrate explosives. As the amountof said amino compounds is increased beyond the preferred ranges abovespecified the sensitivity of the compositions as explosives decreases.This property permits the formulation of ammonium nitrate-amino compoundcompositions of sufficiently reduced sensitivity to allow theirtransportation with safety. I prefer, therefore, to produce and shipcompositions in solution form consisting of ammonium nitrate dissolvedin 15-50% and preferably 20-50% by weight of said amino compounds, basedon the weight of the mixture, and then at the site of use add to saidsolution additional ammonium nitrate to give a satisfactory slurry ofammonium nitrate-amino compound composition consisting essentially ofammonium nitrate and 2-14% by weight, and preferably 6-8%, of said aminocompound, based on the weight of the mixture.

My new compositions suitable either for use as explosives or in thepreparation of explosives consist essentially of a mixture of ammoniumnitrate and the required amount of an amino compound represented by thestructural formula HILT g.

Where R is selected from the group consisting of lower alkyl, lowerhydroxyalkyl, and -C H NH and R is selected from the group consisting ofhydrogen, lower alkyl and C H NH Examples of such amino compoundsinclude primary and secondary amines, including diand tri-primaryamines, and amino alcohols containing 14 carbon atoms. Compounds of thistype include monoand di-methyl-, ethyl-, propyl-, isopropyl-, nbutyl-,secondary butyl-, and isobutyl-amines, ethylene diamine, diethylenetriamine, monoethanolamine, monopropanolamine, butanolamine,2-amino-l-butanol, etc. Solutions of ammonium nitrate in these aminocompounds are preferably first prepared by thoroughly mixing theammonium nitrate with the required amount of amino compound, 20-50% byweight of amino compound, based on the weight of the mixture, ordinarilybeing required. I can then continue the addition of ammonium nitrate togive an explosive composition in the form of a slurry or wet solidcontaining amino compound in the range of 2-14% by weight of aminocompound, and preferably tions.

- hole.

6-8%, based on the weight of the mixture. I prefer, however, totransport the ammonium nitrate-amino compound composition of reducedsensitivity in solution form to the site of use before adding theadditional ammonium nitrate.

The ammonium nitrate utilized in my invention for explosives ispreferably essentially anhydrous pure ammonium nitrate or fertilizergrade ammonium nitrate, either uncoated or coated with various coatingagents, such as resin, diatomaceous earth, etc. Pure anhydrous'ammonium' nitrate is preferred. The amino compound such as, forexample, the monomethylamine or dimethylamine, used in my invention isalso preferably anhydrous.

When the ammonium nitrate and sufficient quantity of r the aminocompound are brought into contact a solution mately 1.5. This increasein bulk density materially increases the etfective explosiveness of thecharge. In mining operations, in particular, the requirement for smalleror fewer bore holes for a given charge materially reduces drillingcosts. 7

My new compositions containing ammonium nitrate as the essentialexplosive ingredient are not subiected to the hazards in production andhandling present in the use of previously known explosives containingammonium nitrate by reason of the fact that they can be easily andsimply prepared at the site at which they are to be used. In manyinstances, the explosives can be prepared directly in the bore hole bysimply placing the ammonium nitrate charge in the bore hole and bypassing a suitable amount of the said amino compound in gaseous orliquid form through the ammonium nitrate therein. Alternately, ammoniumnitrate can be placed in the bore hole and an amount of a solution ofammonium. nitrate in said amino compound sufficient to give a finalammonium nitrate-amino compound composition of the desired compositionand degree of sensitivity added there- 4. paring large amounts of asensitive explosive at any one place, and thereby materially reduces thehazard to life and health of the personnel working in the area.

While my new explosive compositions consist essentially of ammoniumnitrate and said amino compounds, they may also include varying amountsof different additives of the character customarily used in explosivecompositions; such as compositions which increase or reduce the desiredexplosiveproperties of the mixture, or which sensitize or desensitizethem. Other additives include compounds which add oxidizing or reducingpotentials to the explosive compositions, or which catalyze the burningrate thereof, or which reduce the freezing points of the compositionswhen transported in solution form. Fuels which I have found to be usefulin my explosives include ammonia; metals, aluminum or mag nesium;petroleum fractions, wood flour; carbon black; alcohols, such asmethanol or ethanol; etc.

The sensitivity and general utility of my new ammonium nitrate-aminocompound compositions as explosives will vary slightly with theparticularamino compound employed as well as the amount thereof. Theeifectiveness of an explosive mixture containing 7.95% by weight ofmonomethylamine as compared to a number of commercial explosives, usingnitroglycerine as a standard, is

, shown in the following table.

My new explosive compositions can also be prepared in the bore hole bydissolving the said amino compound in a liquid in which it is soluble,such as ethanol when monomethylamine is used as'the amino compound, and

pouring the resulting amine solution over the ammonium nitrate chargepreviously placed in the bore hole. charge can, of course, includecarbon black, ground coal, morpholine, lower alkyl alcohols,dimethylformamide, dimethyl sulfafide, aluminum, sulfur, ferrosilicon,parafiin wax,-resin, or other ingredients ordinarily incorporated intoammonium nitrate explosive composi- The ammonium nitrate-amino compoundcompositions of my invention require primer charges to initiate andpropagate detonation waves through the charge. If

the bore hole in which the explosive is to be detonated is wet,horizontal, or slanting, the ammonium nitrate can he placed in acontainer such as a polyethylene bag or metal cartridge and the aminocompound or ammonium nitrate-amino compound solution introduced into thecontainer or cartridge just prior to its insertion in the bore In thismanner, the hazards of mixing and trans-. porting the finished explosivecompositions are avoided. It should be noted that the incorporation ofthe amino compound into the ammonium nitrate mixture, or theincorporation of an amount thereof to give compositions .containing theamino compound inamounts ranging from- 2-14% 'at the site of usagereduces the necessity of pre- 1 50% nitroglycerine gelatin dynamitecontaining ammonium nitrate An explosive containing approximately 92%ammonium nitrate and 8% carbon black.

of my invention can be prepared at the site of usage The. V

as required and in amounts needed and do not require the shipping,storage and handling precautions required for previous types ofexplosives. 1

While the explosive compositions of my invention containing as little as2% of said amino compounds are sensitized to some extent, about 5-10% ofamino compound such as monomethylamine is required to produce maximumsensitivity. While my ammonium nitrate-amino compound compositions arenot cap sensitive, they have high sensitivity for a mixture of such highdensity; Le, a 92.1% by weight ammonium nitrate-7.9% monomethylaminemixture was found to require only a 70 g. pressed tetryl booster tocompletely detonate a column of explosive having a length of 28 inchesand a diameter of 7 inches. The liquid compositions of my inventioncontaining from about 15-50% amino compound have the same order ofsensitivity as pure ammonium nitrate at sea level pressure.

The following table shows the use of a representative group of additivesin my ammonium-nitrate explosives prepared with monomethylamine, usingdifferent ratios ammo ium n ra eand mono e hy newh h I have found togive effective explosives.

TABLE II Ammo- Mononlum Fuel Percent methyl- Nitrate,

amine Percent Coal Dust 3 Wheat Flour 2 91 Wood (Powdered).... 2 90Garbo Blac 3 90 Ammonia 2 92 2 98 6 94 26 75 The following table setsout some of the physical properties of ammonium nitrate-monomethylamineexplosive compositions. 7

TABLE III Physical properties of ammonium nitrate-monoand di-methylaminesolutions Percent Wt. Monomethylamine 18.1 27.1

abs. 763 691 447 333 79 1. 8 Ignition temperature 400450 C 400-450" 0Percent Wt. Dimethylamiue 24. 97 Vapor Pressure:

Freezing p0 Percent W Density:

A practical method of producing a satisfactory explosive compositionfrom ammonium nitrate and dimethylamine is carried out as follows: A tincan 7 /2 inches ID. by 24 inches long is filled with dry granular highdensity ammonium nitrate and then a solution of ammonium nitrate indimethylamine (75% by weight ammonium nitrate-25% by weightdimethylamine) is added so as to fill all of the voids, using a ratio of0.4 pound of solution to 1.0 pound of granular ammonium nitrate. Theresulting composition consists approximate ly 92% ammonium nitrate and7% dimethylamine.

The use of my new ammonium nitrate-amino compound explosive compositionsis illustrated by the following examples.

EXAMPLE I Four deep bore holes were drilled in a row into a strata ofhard rock overburden containing seams of taconite found to beparticularly difficult to drill and blast 35 feet deep. These holes werecharged with 40 pound cans of explosives. Each can, 7% inches diameterby 16 inches long, was charged with a composition consisting of ammoniumnitrate and dimethylamine in the ratio of one pound of ammonium nitrateto 0.39 pound of a composition consisting of 75.87% amomnium nitrate and24.13% by weight of dimethylamine. Ten of these cans were placed in eachof two of the bore holes and nine cans were placed in each of the othertwo bore holes. A 6 /2 inch diameter Nitramite primer (Du Pont, weight 9pounds) was placed in the middle of the charges (above the fifth can)and a second Nitramite primer was placed under the top can. A singleline of Primacord was run to the two primers. All of the holes containedcon- EXAMPLE II Liquid monomethylamine was added to ammonium nitrate incomminuted form in an amount sufficient to give a solution of theammonium nitrate in the monomethylamine. The resulting compositioncontained 79.56% ammonium nitrate and 20.44% monomethylamine. Commercialcoated ammonium nitrate was then mixed with this solution in the ratioof 0.614 pound of solution to 1 pound of ammonium nitrate. A quart sizetin can was filled with this slurry which consisted of 90.36% by weightof ammonium nitrate, 7.78% by weight of monomethylamine and 1.85% byweight inert (coating agent). The filled can then was buried in soil sothat the top of the can was level with the surface of the ground. Two 37gram blocks of Pentolite booster explosive were taped to the top of thecan. Two No. 8 electric dynamite caps were pressed into holes in thePentolite blocks. The caps were then detonated, initiating detonation ofthe Pentolite and the latter in turn initiating the ammoniumnitrate-monomethylamine compositions. A crater which was about 72 inchesin diameter and 20 inches deep was formed. A comparison test in whichthe same type Pentolite booster was taped to a quart can filled withwater produced only a slight depression in the soil about 16 inches indiameter by 7 inches deep.

This application is a continuation-in-part of my US. patent applicationSerial No. 681,437, filed September 3, 1957, and US. Serial No. 735,987,filed May 19, 1958.

Now having described by invention, what I claim is:

1. Ammonium nitrate compositions suitable for use in the explosive artconsisting essentially of mixtures of ammonium nitrate with 250% byweight, based on the weight of the mixture, of an amine having thestructural formula Hit k! where R is selected from the group consistingof lower alkyl, lower hydroxyalkyl and -C H NH and R is selected fromthe group consisting of hydrogen, lower and C H NH 2. Ammonium nitratecompositions suitable for use as explosives consisting essentially ofmixtures of ammonium nitrate with 2-14% by weight, based on the weightof the mixture, of an amine having the structural formula 1 t where R isselected from the group consisting of lower alkyl, lower hydroxyalkyland --C H NH and R is selected from the group consisting of hydrogen,lower 'alkyl: and C H NH ,7 r v 4. Ammonium nitrate compositionssuitable for use as. explosives consisting essentially of mixtures ofammonium nitrate and 214% by weight, based on the :weight of themixture, of monomethylamine. V

5. Ammonium nitrate compositions suitable for use as explosivesconsisting essentially of mixtures of ammonium nitrate and 214% byweight, based on the weight of the mixture, of dimethylamine.

"in producing explosives consisting essentially of mixtures of ammoniumnitrate with 20-60% of dimethylam'ine, based on the weight of themixture.

No referenees cited UNITED STATES PATENT OFFICE QEHFNATE QECTIQN PatentNo, 2376 137 Marsh 21 Leonard A, Stengel It is hereby certified thaterror appears in the above numbered patent requiring correction and thatthe said Letters Patent should read as corrected below.

Column 5 TABLE II under the heading "f-innrnonxium Nitrate Peroenid andopposite Coal Dust for "0" read 90 Signed and sealed this 5th day ofSeptember 1961a (SEAL) Attest:

ERNEST W. SWIDER Attesting Officer DAVID L. LADD Commissioner of PatentsUSCOMM-DC UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PatentNo.0 2,976 137 March 21 1961 I Leonard A Stengel It is hereby certifiedthat error appears in the above numbered patent requiring correction andthat the said Letters Patent should read as corrected below.

Column 5 TABLE 11,, under the heading "Ammonium Nitrate Percent andopposite Coal Dust for "0" read 90 a Signed and sealed this 5th day ofSeptember 1961,

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of PatentsUSCOMM-DC

1. AMMONIUM NITRATE COMPOSITIONS SUITABLE FOR USE IN THE EXPLOSIVE ARTCONSISTING ESSENTIALLY OF MIXTURES OF AMMONIUM NITRATE WITH 2-50% BYWEIGHT, BASED ON THE WEIGHT OF THE MIXTURE, OF AN AMINE HAVING THESTRUCTURAL FORMULA